Comparison of six different criteria for judging the acceptability of sputum specimens

Abstract

A series of 391 unselected expectorated sputum specimens was examined microscopically, and six different published criteria for judging the acceptability of the specimens were applied. Of the 391 specimens, 234 were found to be acceptable or unacceptable by all six criteria; 157 specimens were discrepant. By the criteria of Murray and Washington and of Barry, 25 and 23% of the specimens, respectively, were rejected; only 19 of 143 specimens which contained potential pathogens as part of their predominant microbial flora were rejected by both sets of criteria. The criteria described by Geckler et al. and Bartlett missed fewer potential pathogens; only 9 or 17% of the specimens, respectively, were found unacceptable. The criteria of Heineman and Radano and of Van Scoy resulted in the greatest percentages of specimens judged unacceptable (28 and 29%, respectively), including 19 and 24% of specimens containing potential pathogens. The reproducibility of sputum screening results was also assessed, comparing the method of Murray and Washington with that of Barry. Six separate slides were prepared from each of 45 different specimens: three samples with purulent or bloody flecks and three samples in which the specimens had been mixed with an applicator swab. Satisfactory reproducibility was observed with both criteria and both sampling methods; no significant differences in reproducibility could be documented in this limited series.

Judging respiratory specimen acceptability for AFB microscopy: visual vs. microscopic screening

“…Several microscopic sputum quality assessment criteria have been developed since the 1970s, aimed primarily at assessing sputum quality prior to bacteriological culture. As squamous epithelial cells (SECs) are only found in the upper respiratory tract, the amount of SECs in a specimen is an indicator of oropharyngeal contamination (Wong et al. 1982), and can be used to indicate whether the specimen originates from deep within the lungs.…”

“…Wong et al. (1982) have used the presence of inflammatory cells as an indication that the specimen originated from a site of active infection and is therefore of acceptable quality; on reanalysing Murray and Washington’s data, Van Scoy (1977) concluded that specimens with more than 25 leukocytes per LPF should be accepted regardless of the SEC count.…”

Randomized trial interpreting sputum quality in a clinical laboratory

“…In 1974, Bartlett proposed that the purity of sputum specimens be rated according to the relative concentrations of polymorphonuclear neutrophils, squamous epithelial cells, and mucus in Gram-stained smears (4). Since his initial report appeared, several others have proposed their own criteria for identifying good-and poor-quality sputum specimens on the basis of cellular content (9,13,14,16,17,20,21). Although the many rating systems in use have been difficult to validate clinically (6, 10), they have intuitive appeal, and several reviewers have warned against basing clinical decisions on culture results from poor-quality specimens (12,15).…”

Prise en charge des infections des voies respiratoires basses de l'immunocompétent. Partie concernant les définitions, l'épidémiologie et les éléments du diagnostic

“…L'association d'un tableau clinique, radiologique et la positivité d'un ECBC de bonne qualité pourraient être suffisants pour affirmer le diagnostic de pneumopathie au germe retrouvé [16]. La pertinence des résultats va dépendre de la qualité du prélèvement déterminée par la présence d'au moins 25 polynucléaires neutrophiles par champ et par la faible quantité de cellules épithéliales (moins de dix cellules par champ) confirmant le caractère distal du prélèvement [123] (niveau 3). Un agent pathogène retrouvé pourra être considéré comme causal s'il est présent en flore pure ou en quantité suffisante (plus de 10 7 colonies formant unité par millilitre) [45].…”